在骨科手術中，骨板廣泛地被用來治療各種部位的骨折，而新型的鎖定式骨板(Locking plate)其螺絲與骨板可用螺紋系統結合，因此比傳統的動態加壓骨板(dynamic compression plate)要能提供更佳的穩定度。然而螺紋幾何所造成的凹口經常產生應力集中進而降低元件之疲勞壽命，而不同材料有不同的凹口敏感度，使其凹口對疲勞壽命有不同的影響。因此本研究目的為探討螺紋設計與不同材料對鎖定式骨板機械性能優劣性之影響。
　　在本文中，分為生物力學測試以及有限元素分析兩部分，在生物力學測試方面，總共對九種骨板進行降伏測試與疲勞測試，而在實驗後得到位移、負載之關係而計算出其彎曲徑度、降伏強度與疲勞壽命；而在有限元素分析方面，利用SolidWorks建立三維骨板模型並匯入ANSYS來進行模擬，其負荷情形與邊界條件和機械測試相同，並得到有限元素分析數值之最大張應力與位移，並將生物力學測試與有限元素分析做一相關性的比較。
　　由機械測試結果得知，鈦合金骨板一但有螺紋設計後，其疲勞壽命將大幅下降，而不鏽鋼因較不受凹口影響，故螺紋引起之凹口效應較不顯著。有限元素分析結果顯示，當最大應力發生在螺紋頂角時，便會引發因螺紋產生的凹口效應。F1314不鏽鋼有著比316L不鏽鋼高的靜態強度，且也較不受凹口效應影響，故其疲勞壽命為本研究表現最佳之材料。此生物力學研究結果可以提供給相關工程師做為改良鎖定式骨板之設計参考。

　　Osteosynthesis plates have been used to treat various types of fracture in surgical operation. Locking plate can provide more stability than traditional dynamic compression plate because its locking screw can lock on plate by threaded hole . However, the notch of thread geometry often produces stress concentration that decreases the fatigue life of components. There are various materials with different notch-sensitivity that resulted the different effect on fatigue life. Thus the purpose of this study was to investigate the mechanical property of locking plate with different materials and thread design.
　　In biomechanical testing, both the yielding test and fatigue test were performed. In finite element analysis, a 3D finite element model was carried out to simulate the situation of biomechanical testing. Consequently the maximal tensile stress and displacement were calculated and compared with each other for both biomechanical test and finite element analysis.
　　From the results of biomechanical test, the titanium alloy plates with thread design significantly shorten the fatigue life . The fatigue life of stainless steel plate is not significantly shorten by thread design, because it's not sensitivity to notch. The finite element analysis shows the notch effect is cause of thread, while the tip of thread with maximal stress. Both stainless steel F1314 and stainless steel 316L have lower notch-sensitivity, but stainless steel F1314 has higher static strength, so its performance of fatigue life is the best in this study. The results of this study could directly provide the engineer for new design of improves the locking plate.

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